Welding Terms Part-6 (L&M)

     Dear Readers.

This is continuation of Part-5. Welding is a highly technical field requiring specialized acronyms and abbreviations. This article will be a valuable resource for anyone looking to enhance their knowledge of the Welding Works.

Lap Joint – A joint between two overlapping members in parallel planes.

Laser – A device that provides a concentrated coherent light beam. Laser is an acronym for Light Amplification by Stimulated Emission of Radiation.

Laser Beam Cutting – A process that severs material with the heat from a concentrated coherent beam impinging upon the workpiece.

Laser Beam Welding – A process that fuses material with the heat from a concentrated coherent beam impinging upon the members to be joined.

Layer – A stratum of weld metal or surfacing material. The layer may consist of one or more weld beads laid side by side.

Leads – These are the lines from the machine to what you are welding that carry the current.

Leg of Fillet Weld – The distance from the root of the joint to the toe of the fillet weld.

Liquidus – The lowest temperature at which a metal or an alloy is completely liquid.

Local preheating – Preheating a specific portion of a structure.

Local stress relief heat treatment – Stress relief heat treatment of a specific portion of a structure.

Longitudinal sequence – The order in which the increments of a continuous weld are deposited with respect to its length.

Machine Welding – Equipment performs the weld while a person watches to make sure it is working right. They will also visually inspect the completed weld.

Macro Testing – A destructive testing method where the sections of a weld are polished, etched and examined under a microscope for defects.

Mandrel – A metal bar serving as a core around which other metals are cast, forged, or extruded, forming a true, center hole.

Manifold – A multiple header for interconnection of gas or fluid sources with distribution points.

Manual Welding – A welding process where the torch or electrode holder is manipulated by hand.

Mash Seam Welding – A seam weld made in a lap joint in which the thickness at the lap is reduced to approximately the thickness of one of the lapped joints by applying pressure while the metal is in a plastic state.

Mechanical Bond – The adherence of a thermal-spray deposit to a roughened surface by particle interlocking.

Mechanized Welding – Welding with equipment where manual adjustment of controls is required in response to variations in the welding process. The torch or electrode holder is held by a mechanical device.

Melting Point – The temperature at which a metal begins to liquefy.

Melting Rate – How much of the rod (electrode), wire, or TIG rod is melted in a certain amount of time. Or the temperature range between solidus and liquidus.

Melt-Through – Visible reinforcement produced on the opposite side of a welded joint from one side.

Metal-Arc Cutting – The process of cutting metals by melting with the heat of the metal arc. Arc metal cutting is a thermal cutting process that uses an arc between an electrode and the workpiece to melt and remove metal.

Metal-Arc Welding – An arc welding process in which a metal electrode is held so that the heat of the arc fuses both the electrode and the work to form a weld.

Metal Cored Arc Welding – A tubular electrode process where the hollow configuration contains alloying materials.

Metal Cored Electrode – A composite tubular electrode consisting of a metal sheath and a core of various powdered materials, producing no more than slag islands on the face of the weld bead. External shielding is required.

Metal electrode – A fillet or non-filler metal electrode, used in arc welding or cutting consisting of a metal wire or rod that has been manufactured by any method and that is either bare or covered with a suitable covering or coating.

Metallizing – A method of overlay or metal bonding to repair worn parts.

Metallic bond – The principal bond which holds metals together and which is formed between base metals and filler metals in all welding processes.

Method – An orderly arrangement or set form of procedure to be used in the application of welding or allied processes.

Microprocessor – One or more integrated circuits that can be programmed with stored instructions to perform a variety of functions.

MIG – It may be technically called GMAW, but in the shop Mig welding uses a solid steel wire rolled up on a spool and fed through a welding lead with a liner in it. Drivers push, pull or both to feed the wire through the lead to the welding gun.

Mixing Chamber – It is part of a welding or cutting torch in which the gases are mixed for combustion.

Molecular Weight – The sum of the atomic weights of all the constituent atoms in the molecule of an element or compound.

Molten weld pool – The liquid state of a weld prior to solidification as weld metal.

Monochromatic – The color of a surface that radiates light, containing an extremely small range of wavelengths.

MQP – Manufacturing Quality Plan. It is a basic test during manufacturing process.

MTC / MTR – Material Test Certificate / Material Test Report.

Multi-Impulse Welding – The making of spot, projection, and upset welds by more than one impulse of current. When alternating current is used each impulse may consist of a fraction of a cycle or a number of cycles.

Multipass Welds – When multiple welds are applied to one project.